Mercedes-Benz made minor updates to its flagship S-Class sedans for 2009. Upgrades across the line include new power window switches, as well as redesigned steering-wheel-mounted Touch Shift buttons, which drivers can use to manually shift the seven-speed automatic transmission, which comes standard in all S-Class sedans. The automaker also updated the S550 and S550 4Matic trims by equipping them with the Premium 1 package, which adds ventilated front seats, a wood and leather steering wheel, and a trunk closer at no extra charge. In addition, the optional Distronic Plus Package (which includes adaptive cruise control) now comes with a parking guidance system and a Blind Spot Assist system, which uses radar sensors to monitor the driver's blind spot and signals the driver with a red hazard symbol if another vehicle enters it. The system also sounds an audio alarm if the driver attempts to change lanes when another vehicle occupies the driver's blind spot. The '09 S-Class sedans retain the shapely styling of the previous year, with flared wheel arches and a V-shaped trunk lid that give the vehicles a muscular yet refined appearance. Mercedes offers the S-Class in five trims, starting with the S500, which jumps out from 0 to 60 in just 5.4 seconds, thanks to its 382-hp, 5.5-liter V8 engine. Such features as 14-way power-adjustable front seats, leather upholstery and trim, three-level heated front seats, and hand-polished Burl Walnut wood trim all come standard. The S550 4Matic trim adds Mercedes' all-wheel-drive system. Stepping up a notch, the S600 sedan retains its powerful 510-hp, 5.5-liter V12 engine, and pampers drivers with such luxury amenities as Drive-Dynamic multicolor front leather seats with a four-stage massage function, power rear slide window shades, noise-reducing glass, and a panorama sunroof. At the top of the line, both the S63 AMG and S65 AMG are powered by AMG-built engines. A 518-hp, 6.2-liter V8 engine drives the S63, while the S65 AMG retains its whopping 604-hp, twin-turbo 6.0-liter V12. Both feature components tweaked by AMG, Mercedes' in-house tuner, including AMG-designed sport seats, F1-inspired manual shifters, an AMG sports exhaust system, a high-performance braking system, 20-inch AMG five-spoke alloy wheels, and AMG-calibrated Active Body Control, as well as AMG exterior styling. All S-Class four-door sedans seat five passengers, and are rear-wheel-drive vehicles, except for those equipped with the 4Matic all-wheel-drive system. All include a wide range of safety features, including the Pre-Safe accident preparation system, front active head restraints, rollover sensors, and a wide range of airbags, including front and rear side head curtain airbags.